To edit a PDF and keep the same font, the new characters have to be drawn with the font the document already uses. There are three honest ways to get there: install that exact font if you own it, accept a close match and check it, or use an editor that types with the font embedded in the PDF itself. PDF Textfix takes the third way. It writes your correction with the embedded font, and when that font lacks a character you type, it draws only that character from elsewhere, in a documented order, and marks it. Below: why fonts get swapped, each option with its catch, the steps in PDF Textfix, and how to check the result.
The full font. Every glyph its designer drew.
The embedded subset. Only the glyphs of “INVOICE DATE”: there is no B, F or G to type.
Why do PDF editors swap the font?
Because the font in a PDF is usually not a font your Mac can use. When an app exports a PDF, it embeds the typeface inside the file, and to keep the file small it often embeds a subset: only the characters the document needs. The standard marks a subset with a prefix, and “The tag shall consist of exactly six uppercase letters”, so a subset of IBM Plex Mono is named something like AAAAAD+IBMPlexMono.
That subset is enough to display and print the page anywhere. It is not an installed font, it may lack most of the alphabet, and macOS will not offer it in any font menu. An editor that draws new text with installed fonts then has nothing to draw with, so it substitutes the nearest font it has. The guide to why editing changes the font walks through the symptoms in more detail, and the glossary entry on embedded subset fonts defines the term.
What are your options for keeping the same font?
Option 1: Install the font, if you own it
If the document was made with a font you have a licence for, installing it gives an editor that relies on installed fonts what it needs. Apple’s Font Book guide states the requirement: “To use fonts in your apps, you need to install the fonts using Font Book.” Acrobat’s help states the same rule from the editing side: “To edit text using a specific font, you must have that font installed on your computer. If the font isn’t installed but is embedded in the PDF, you can only change the text’s color or size.”
The catch: you need the same font, ideally in the same version. A newer release of a typeface can have different spacing, and a commercial font you do not own cannot be installed honestly. Fonts made for one company, such as a bank’s or a university’s house typeface, may not be sold to the public at all.
Option 2: Accept a near match, and check it
An editor that types with installed fonts has to pick a stand-in when the document’s font is missing. Acrobat’s help states how Acrobat handles it: “When editing text in a PDF, Acrobat may use a fallback font if the original font isn’t available on your system.” It also lets you choose which one: “To set a fallback font for text editing, select an option from the Fallback font for Editing dropdown menu.” For any other editor, check its documentation for its own rule.
A near match can be fine for a number in a table or a word in small print. In a name, a heading or a signature line, readers notice a different “g” or a wider “a”. If you take this route, zoom in after the edit and compare.
Option 3: Edit with the font that is already in the file
The subset embedded in the PDF has the exact shapes of the characters the document already uses. An editor that reuses those shapes needs nothing installed, and the corrected word matches its neighbors as long as the subset holds the letters you type. When it does not, the editor must say so, rather than quietly mixing two fonts. This is how PDF Textfix works, and the next steps show it on the demo documents.
Step 1: How do you see which font a line uses?
Open the PDF in PDF Textfix, select the line and press Return. The bar under the pages names the line’s font as the file names it, whether it is embedded, and its size. On the demo invoice’s date, it shows IBM Plex Mono as an embedded subset at 9.5 points:
A font the file does not embed at all is listed in the Issues pane (⌥⌘I), and the bar calls it “not embedded”. To list every font of a file at once, Terminal’s pdffonts from Poppler included, see the guide to finding the fonts in a PDF.
Step 2: What happens when the subset lacks a letter you type?
Type the correction in the editor over the line. Characters the embedded font already holds are written with it. For any character it lacks, PDF Textfix searches in a fixed order and stops at the first place that has it:
- another copy of the same font inside the file (exporters sometimes embed one font twice, as two subsets);
- the same font installed on your Mac;
- the closest standard font.
You type é. The line’s own font has no é.
- Another copy of the same font in the file.
- The same font, installed on your Mac.
- The closest standard font.
The demo cover letter shows the order at work. pdffonts lists one subset per weight in it, AAAAAB+IBMPlexSerif-SemiBold, the weight of the heading, and AAAAAC+IBMPlexSerif-Regular, so the first step finds no second copy of the heading’s font. Neither subset has an “é”, because the letter never used one, and stock macOS does not install IBM Plex Serif. So when the writer corrects her name in the heading to Renée Okafor, every other letter stays in the cover letter’s serif and the “é” comes from the third step, a standard serif:
The marks tell you what happened to each character. Orange means it was drawn with another font. An underline means it was written with another copy of the line’s own font. Red means no font in the file or on your Mac can draw it; the edit cannot be applied until you change that character, and when a close alternative exists, ⌃⌘U puts it in.
Step 3: How do you read the bar and the Issues pane?
When a fallback was used, the bar’s first line says so and names it, here Times-Bold, while its second line still names the line’s own embedded font:
After you apply the edit, the Issues pane lists every fallback font your edits used, so you can review them before saving. It also names fonts whose licence limits edits. When an embedded font’s licence is Restricted or Preview & Print, PDF Textfix still lets you edit with the characters the file already has for it, but never builds a new font from it: a missing character comes from another font if one fits, and otherwise the edit is refused with the licence as the reason.
Step 4: How do you check that the new letters match?
- Zoom in. Press ⌘+ until the line fills the window, and compare each new character with the same character elsewhere on the page.
- Look for orange. Any marked character is in another font. Decide whether that is acceptable, or reword so the subset’s own letters do the work: “Okafor” needs nothing new, “Renée” does.
- Check the spacing. An edit that would move any other character on the page is refused with the reason. When the new text would run into the words after it, PDF Textfix moves the rest of the line to make room and says so in the bar; Keep Following Text in Place puts it back, and Shift Rest of Line (⌃⌘R) moves it by hand. Look at the gap after your edit all the same.
- List the fonts again. After you save,
pdffontson the saved file shows the original subsets plus one more font when a fallback character was needed: PDF Textfix never modifies an existing font object, and adds a separate one used only by the inserted characters. - Open the saved file in another viewer, such as Preview, and read the line there too.
What if the PDF does not embed its font at all?
Some files name a font without carrying it. That is common for the standard fonts every PDF viewer must provide, such as Helvetica, Times and Courier, and for a few core system fonts. A viewer draws those with a font of its own, so the page can look slightly different from one app to another before anyone edits it. PDF Textfix edits such lines too, and the bar says “not embedded” in its font line. Characters within that font’s character set are written under the same font name, so a viewer draws them exactly as it draws the rest of the line; any others follow the fallback order above.
The one exception is PDF/A, the archival format, which requires embedded fonts. In a PDF/A file, a missing character always comes from an embedded font, never from a font the file would only name.
When is keeping the font not worth the fight?
A one-word fix in body text usually works, because body text uses most of the alphabet and the subset holds it. A heading, a logo line or a word in a decorative typeface is different: the subset may hold only the dozen letters that heading needed, and a new word would come out half in fallback. In that case you have three better moves:
- Reword with the letters you have. Look at which letters the heading already uses. A synonym built only from them stays in the original face, and the orange marks tell you at once whether it does.
- Ask for the source file. The person who made the document has the full font and can export a corrected copy in a minute.
- Rebuild the line where it was made. For a heading set in a font you own, recreating the page in the original app gives you every letter.
PDF Textfix will show you in orange exactly which letters are missing before you apply anything, so you can make that decision with the evidence on screen rather than after the file is sent.
What can PDF Textfix not promise?
- A character the file never had cannot come from the file. It comes from your Mac or from a standard font, and it is marked.
- What you see while typing can differ for a moment. In some embedded fonts, the editor shows the line in the closest installed font while you type; once you apply the edit, the page shows it in the line’s own font. The page is what Save writes.
- Some fonts cannot take new text. Fonts made of pictures (Type 3), vertical text, right-to-left and joined scripts, and Chinese, Japanese and Korean encodings are locked, and the line says why.
- It does not change a font or a size on purpose. It keeps the one the line has.
The comparison of editors on keeping the font sets each vendor’s documented rule side by side.
Questions people ask
Can I make edited text match the original font without having the font?
Yes, when the letters you type are in the subset embedded in the PDF. PDF Textfix writes them with that subset. Letters it lacks come from elsewhere and are marked. PDF Textfix is free to try. Your first 5 line edits save clean. After that, saved files carry a watermark until you buy once. The pricing page has the details.
Why does my PDF editor say a font is missing when the PDF displays fine?
The PDF carries an embedded copy to display itself, often only the characters it uses. Editors that type with installed fonts look for the font on your Mac and do not find it.
How do I match a font from a PDF?
Identify it first: the font’s name after the plus sign, such as IBMPlexSerif in AAAAAC+IBMPlexSerif-Regular, is the typeface the document was set in, and the guide to finding the fonts in a PDF shows where to read it. Then install that typeface from its maker, if its licence allows, so that the apps you use to make new documents can set text in it. The subset inside the PDF is not an installable font.
Will the new text be the same size as the old?
Yes. PDF Textfix writes your characters at the line’s own size and does not change sizes. A wider or narrower word changes the line’s length, not its size; when a wider word would run into the text after it, the rest of the line moves to make room, and the bar says so.
Why can't I change the font on a PDF?
Because the text on a PDF page is drawn with the fonts the file carries, often subsets that hold only the characters the document uses. Setting a word in another typeface takes an editor that can embed a new font, and a new size changes where every following character sits. PDF Textfix deliberately keeps the line’s font and size; the answer on changing the font, size or color says what to use instead.
